Field of the Invention
The present invention relates to a fuse resistor, and more particularly to a fuse resistor in which functions of a fuse and a resistor may be performed together, resistive elements and a temperature fuse are installed on a substrate in a surface mount type and thus automation may be facilitated, the plural resistive elements are properly disposed and thus the functions of the fuse and the resistor may be effectively performed, and a manufacturing method thereof.
Description of the Related Art
In general, in an electrical circuit of a large electronic product, such as an LCD TV or a PDP TV, or a portable electronic apparatus, such as a smartphone or a tablet PC, a protective device, such as a thermal fuse resistor, to prevent malfunction of the apparatus caused by inrush current, internal temperature rise or continuous supply of overcurrent, generated while powered on or a battery is being charged, is provided at a power input terminal of the electrical circuit so as to protect a power circuit.
Such a fuse resistor includes a resistive body and a temperature fuse and the resistive body and the temperature fuse are connected in series by lead wires.
Further, in the fuse resistor, the resistive body and the temperature fuse are packaged with a case so that other electronic parts are not damaged by scraps generated when a fuse element is broken, and the inside of the case is filled with a filler.
Here, the filler is a slurry type filler including silicon oxide (SiO2) in consideration of heat resistance, conductance, and a thermosetting property, and the case is generally formed of ceramic like that of conventional resistors.
The end of the lead wire is extended to be withdrawn from the case, and the conventional fuse resistor is installed on a printed circuit board by soldering the ends of the lead wires to the printed circuit board so that the resistive body and the temperature fuse are installed erectly.
Therefore, if inrush current is introduced into the above fuse resistor, the fuse resistor restricts the inrush current to designated current using the resistive body and, if overcurrent is introduced into the fuse resistor, the fuse resistor conducts heat generated from the resistive body to the temperature fuse through the filler and shorts the circuit so that the fuse element formed of lead in a solid state or high polymer pellets may be broken, thus protecting the electrical circuit of an electric home appliance.
With reference to FIG. 10, Korean Registered Patent NO. 10-1060013 discloses a temperature fuse resistor including a resistive body, a temperature fuse provided to short a circuit by exothermic reaction of the resistive body, a lead wire connecting the resistive body and the temperature fuse in series, a case, one surface is opened so as to receive the resistive body and the temperature fuse under the condition that the end of the lead wire is withdrawn from the case, provided with a withdrawal groove on one side wall of the case so as to withdraw the lead wire, and a filler filling the inside of the case so that the resistive body and the temperature fuse are inserted into the filler and including silicon oxide, wherein the case is formed by injection molding using a thermosetting resin having lower heat resistance than the filler.
However, in case of the temperature fuse resistor of the above Korean Registered Patent, the resistive body is provided at only one side of the temperature fuse and thus, heat generated if rated current is applied is not dispersed and a product temperature in a normal state is raised.
Further, in the temperature fuse resistor of the above Korean Registered Patent, a lead wire connecting the resistive body and the temperature fuse and lead wires extended to the outside of the case are required and thus, manufacture of such a temperature fuse resistor is difficult to automate.